Um, there weren't
that many New Zealand troops in the ANZAC forces. We balanced them out pretty nicely...
As Long Tan suggests.
(just kidding!) 
I don't believe that NZ forces really served side-by-side with Aus forces after the early stages of WWII. I could be wrong, but I think "Anzac" just became an affectionate, traditional moniker for Australian troops, much like your "G.I.".
I'll do a search and try to clarify.